Abstract: S16.00002 : Evaporation from a semi-infinite porous medium: The role of capillary flow

Authors:

H.K. Navaz(Kettering University)

B. Markicevic(Kettering University)

S.J. Paikoff(DTRA)

The liquid evaporation from the semi-infinite porous medium is solved
numerically using the dynamic capillary network model in which the interface
shape and multiphase flow front thickness between dry and fully wet parts of
porous medium are tracked in time. Both convective and diffusion mass
transport limited regimes are identified and liquid pseudo-velocity due to
the evaporation is calculated. The numerical analysis is extended for
in-parallel capillary flow and evaporation liquid transport, and again, the
changes of the interface shape and multiphase flow front thickness are
investigated. It turns out that the convective evaporation is prolonged due
to the capillary flow as evaporated liquid close to the evaporating boundary
is replenished by capillary flow. However, the evaporation curve has an
elongated ``tail'' for longer evaporation times as capillarity tends to
transport the liquid deeper into the porous medium. The contributions of the
capillary flow and the mass transport on the overall evaporation dynamics is
best visible by comparing the liquid pseudo-velocity for pure evaporation
and evaporation with capillary flow. Two pseudo-velocities are equal for
time for which there is a transition from convection to diffusion controlled
evaporation. In this point, the remaining liquid is always distributed in
the multiphase pattern, where the thickness of the multiphase region depends
on capillary flow and mass transport rates.

To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2011.DFD.S16.2